甘肃省早子沟金矿床构造演化与成矿

发布时间：2018-08-07 15:26

【摘要】：早子沟金矿是西秦岭夏河-合作金矿带近年来发现的百吨级别的中低温热液型矿床,深部仍有巨大的找矿潜力。早子沟金矿断裂构造控矿特征明显,金矿体分布与断裂构造关系密切,在区域上具有典型性和代表性。众多专家学者对该矿床的地球化学、成矿物质来源、矿床成因等方面开展了大量的研究,但对矿区构造的研究较为薄弱。本文就是在老矿山找矿项目的资助下,在总结前人资料的基础上,通过野外对不同方向构造形迹的细致观测和室内综合分析,从构造应力场的角度出发,探讨构造与成矿的关系,旨在为深部找矿预测提供指导。取得的主要进展包括:夏河-合作地区处于夏河-礼县高角度逆冲推覆构造带内,区域性逆冲断层呈NW向展布,总体向SW倾,区内广泛发育层间尖棱褶皱、“Z”字形褶皱,指示了区域逆冲推覆构造为由SW向NE运动。在野外实地对控矿构造详细观测分析的基础上,利用构造解析法、节理分析法、共轭剪节理法和断层擦痕分析法,通过吴氏网投图分析,确定了早子沟金矿床多期次构造活动的主应力方向,并根据叠加和切割关系以及成岩成矿时代的确定,推断了应力作用的期次和时代;从而将早子沟金矿的构造应力场划分为3期5个阶段,即成矿前的海西期基底变形、印支早期区域变形和岩浆侵位阶段,成矿期早阶段为印支中期,NE-NEE向的挤压导致了矿区SN向和NE向断裂中发生以金为主的成矿作用,晚期阶段为印支晚期,NWW向的挤压导致了NW向缓倾角断裂中发生以锑为主的成矿作用;成矿后阶段断裂活动导致了矿体局部被错断。进一步分析了不同阶段断裂活动及其成矿特征,认为构造应力场演化与成矿作用具有一致性的特征,断裂的多期次活动有利于形成富大矿体,进而指出NE向主断裂与旁侧分支断裂的复合部位以及NE向断裂与NW向断裂的交汇部位为深部寻找富大矿体的有利空间。
[Abstract]:The early zicogou gold deposit is a middle and low temperature hydrothermal type deposit found in the Xia he cooperative gold belt in Western Qinling Mountains in recent years. The deep part still has great potential for ore prospecting. The characteristics of ore control in the fault structure of the early zicogou gold deposit are obvious, the distribution of gold ore body is closely related to the fracture structure, and it is typical and representative in the region. The geochemistry of the bed, the source of metallogenic material and the genesis of the deposit have been carried out a lot, but the research on the structure of the mining area is relatively weak. This paper is on the basis of the old mine prospecting projects, on the basis of summarizing the previous data, through the careful observation and the indoor comprehensive analysis of the structural trace of different directions in the field, from the tectonic stress. On the field point of view, the relationship between structure and mineralization is discussed in order to provide guidance for deep prospecting and prediction. The main progress has been made as follows: the Xia he cooperative area is located in the Xia he Lixian high angle thrust nappe belt, the regional thrust fault is distributed in the direction of NW, as a whole, to SW, and in the region, there are widely developed interlayer prismatic folds and "Z" shaped folds. The regional thrust nappe structure is directed from SW to NE. On the basis of detailed observation and analysis of the ore control structure in the field, the main stress direction of the multiple tectonic activity of the early zisogou gold deposit is determined by the structural analytic method, the joint shear method, the conjugate shear joint method and the fault scratch analysis method. The relationship between superposition and cutting, as well as the determination of the age of diagenesis and mineralization, infer the period and time of the stress action, and the tectonic stress field of the early zigogou gold deposit is divided into 3 stages, that is, the deformation of the Hercynian basement before the mineralization, the early Indosinian regional deformation and the magma emplacement stage, the early stage of the metallogenic period is the mid Indosinian and NE-NEE direction extrusion guide. The metallogeny of gold mainly occurred in the SN direction and NE faults in the mining area. The late stage was late Indosinian. The extrusion of NWW direction resulted in the mineralization of antimony dominated by the NW to the slow dip fault, and the post metallogenic stage fracture activity resulted in the partial fault of the ore body. In order to make the evolution of tectonic stress field consistent with the mineralization, the multiphase activity of the fracture is beneficial to the formation of rich ore bodies, and then points out that the compound part of NE to the main fault and the lateral branch and the intersection of the NE fault and the NW fault is the favorable space for the deep exploration of the rich ore body.
【学位授予单位】：中国地质大学(北京)
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P618.51

【参考文献】